The influence of particle characteristics on the index void ratios in granular materials

Abstract

The goal of this paper is to assess the effects of particle and specific gravity characteristics (e.g. shape, size, and specific gravity) on the limiting void ratios emax and emin of granular matter. To assess the effect of specific gravity, two different types of materials—glass beads and natural sands—were used. Particle characteristics such as roundness (R), sphericity (S) regularity (ρ), the average of R and S, were calculated through image analysis techniques after obtaining high-quality microscope images of individual grains. The German DIN standards were strictly followed to determine the extremities of the void ratio. Experimental data were used to investigate the effects of the particle characteristics on the relative density of soils. The results show the significant effect of the mean grain size (D50) on the extreme void ratios of poorly graded glass as well as the significant effect of Cu but negligible effect of D50 on the extreme void ratios of sand. The effect of the specific gravity of the materials was also examined. The results were used to develop models dependent on both particle shape and specific gravity, which were validated by comparison with results of previous studies.